[PM] Sink the no-op pass parsing logic into the .def-based registry to

[PM] Sink the no-op pass parsing logic into the .def-based registry to
simplify things. This will become more important as I add no-op analyses
that want to re-use the logic we already have for analyses in the
registry. For now, no functionality changed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225238 91177308-0d34-0410-b5e6-96231b3b80d8